CN111069363B - Method for realizing bending forming process of in-situ nano reinforced high-strength and tough steel - Google Patents
Method for realizing bending forming process of in-situ nano reinforced high-strength and tough steel Download PDFInfo
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- CN111069363B CN111069363B CN201911304817.7A CN201911304817A CN111069363B CN 111069363 B CN111069363 B CN 111069363B CN 201911304817 A CN201911304817 A CN 201911304817A CN 111069363 B CN111069363 B CN 111069363B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
- B21D5/14—Bending sheet metal along straight lines, e.g. to form simple curves by passing between rollers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
- B21D5/004—Bending sheet metal along straight lines, e.g. to form simple curves with program control
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
- B21D5/006—Bending sheet metal along straight lines, e.g. to form simple curves combined with measuring of bends
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Abstract
The invention provides a method for realizing a bending forming process of in-situ nano reinforced high-strength and tough steel, relates to the technical field of metal forming, can greatly improve the forming quality and the structural reliability of roll-bending plates, is energy-saving and efficient, can reduce technical risks, and obviously improves the formability and the forming precision; the method comprises the following steps: s1, calculating the curvature radius before springback according to the curvature radius of the required plate; s2, determining the pressing amount of the upper roller according to the curvature radius before springback; s3, inputting the pressing amount, the friction coefficient, the rotating speed and the rolling pass of the upper roller into a model for simulation; s4, obtaining the forming precision and forming performance of the plate according to the circumferential strain distribution and residual stress distribution; s5, judging whether the forming precision and the forming performance meet the requirements or not; if yes, the method is applied to actual production; otherwise, the friction coefficient, the rotation speed and the rolling pass are adjusted, and the process re-enters S3. The technical scheme provided by the invention is suitable for the roll bending forming process.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of metal forming, in particular to a method for realizing a bending forming process of in-situ nano reinforced high-strength and high-toughness steel.
[ background of the invention ]
The existing steel forming and bending process has the disadvantages of unreasonable process arrangement, multiple processes, unreasonable process parameter selection, unreasonable collocation of all process parameters and higher requirement on operator experience, so that the production cost is higher, the product quality is lower and the yield is not high.
The cold-bending forming of the plate needs to consume a large amount of manpower and material resources in the trial-manufacture process, and meanwhile, the process conditions and parameters in the forming process are not easy to control, and particularly for newly developed high-strength and high-toughness steel, the process becomes more complicated. Many domestic and foreign researches on the plate forming process of the three-roller plate bending machine are reported, but most of the researches are about common steel grades, and the strength of the material is not very high. The high-strength plate is more and more required by equipment development, but the cold bending formability of the in-situ nano-reinforced high-strength and high-toughness steel thick plate is not clear along with the yield and the strength of the high-strength plate, and the high-strength and high-toughness steel thick plate is required to have good forming quality when a rolled plate is formed in order to be suitable for the service environment of a target material under a specific condition. Roll bending forming is a process of undergoing large displacement, large rotation and large deformation, has the characteristics of obviously complex geometric nonlinearity, material nonlinearity, boundary condition nonlinearity and the like, relates to a plurality of factors of elastic-plastic deformation, frictional contact and the like of a metal plate, is difficult to grasp a forming rule, and makes the design and control of a forming process very difficult, so that the plate is easy to generate defects of cracking, wrinkling, resilience and the like, and the dimensional precision and the surface quality of a structural part are influenced, thereby further influencing the subsequent assembly process. Springback is always a key problem and a difficult problem concerned in the industrial fields of processing and manufacturing and the like, the springback problem is not a simple elastic unloading process, but the plastic accumulation of a plate in the whole processing process is closely related to a plurality of factors such as the shape and the size of a die, material properties, frictional contact and the like, so that the effective springback control is the direction of deep research and discussion of many scholars at home and abroad, and comprises various aspects such as unidirectional tensile deformation to cyclic loading deformation, numerical simulation to experimental verification, springback prediction to springback control and the like. At present, the automation level of the cylinder rolling process of a large three-roller plate rolling machine in China is still in a primary stage, manual operation is mainly relied on, and the curvature of a rolled and bent formed rolled cylinder is mostly ensured by using a clamping plate.
Therefore, there is a need to develop a method for implementing a bending process of in-situ nano-reinforced high-strength and toughness steel to overcome the shortcomings of the prior art and to solve or alleviate one or more of the above-mentioned problems.
[ summary of the invention ]
In view of the above, the invention provides an implementation method of a bending forming process of in-situ nano reinforced high-strength and high-toughness steel, which can greatly improve the forming quality and the structural reliability of roll-bending plates, is energy-saving and efficient, can reduce technical risks, and can significantly improve the formability and the forming precision.
The invention provides a method for realizing a bending forming process of in-situ nano reinforced high-strength ductile steel, which is characterized by comprising the following steps of:
s1, calculating the curvature radius before springback according to the curvature radius of the plate to be formed;
s2, determining the pressing amount of the upper roller according to the curvature radius before springback;
s3, inputting the pressing amount of the upper roller, the friction coefficient, the rotating speed and the rolling pass into a model established by finite element analysis software for simulation operation to obtain a simulation result;
s4, analyzing the circumferential strain distribution and residual stress distribution of the roll bending formed plate in the simulation result to obtain the forming precision and forming performance of the roll bending formed plate;
s5, judging whether the forming precision and the forming performance of the roll bending formed plate meet the requirements of actual production or not; if the requirements are met, applying the values of the upper roller pressing amount, the friction coefficient, the rotating speed and the rolling pass corresponding to the plate to actual production; otherwise, the friction coefficient, the rotation speed and the rolling pass are adjusted, and the process re-enters S3.
The above aspect and any possible implementation manner further provide an implementation manner, and the formula for calculating the radius of curvature before springback in S1 is:
in the formula, ρ1Radius of curvature of the sheet to be formed, p0-radius of curvature of the sheet before springback, n-hardening index; t-the thickness of the plate; a-a correction factor; sigmas-yield strength, MPa; b ═ n +2) E, E young's modulus, GPa.
The above aspect and any possible implementation manner further provide an implementation manner, where the relation between the radius of curvature before springback and the pressing amount of the upper roll in S2 is as follows:
ρ0＝-0.0039X3+2.5239X2-550.34X+41794 (2)
in the formula, X-the amount of pressing down of the upper roll, rho0-radius of curvature of the sheet before springback.
The above aspects and any possible implementations further provide an implementation in which the values of the friction coefficient, the rotation speed and the rolling pass are determined based on parameters of the actual production facility and historical data.
The above aspects and any possible implementation manner further provide an implementation manner, wherein the friction coefficient is in a range of 0.15 to 0.25, the rotation speed is in a range of 0.05 to 0.07rad/s, and the rolling pass is in a range of 5 to 7.
The above aspect and any possible implementation further provides an implementation, wherein n is 0.038, σs＝824.1MPa，t＝45mm，E＝204GPa，a＝1.75×10-5。
The above-described aspect and any possible implementation manner further provide an implementation manner, in S5, the values of the upper roll reduction amount, the friction coefficient, the rotation speed, and the rolling pass are applied to actual production: dividing the cylinder into three sections according to the structural form of the cylinder of the plate to be formed, and performing roll bending on each section independently, wherein the roll bending process of the three sections adopts the upper roller pressing amount, the friction coefficient, the rotating speed and the rolling pass obtained in the steps; and after the roll bending is finished, welding and assembling the three sections of circular arcs, and then performing subsequent processes.
According to the above aspects and any possible implementation manner, an implementation manner is further provided, and if different friction coefficients, rotation speeds and rolling passes are input into the model for simulation to obtain multiple groups of friction coefficients, rotation speeds and rolling passes meeting the actual production requirements, orthogonal tests are performed on the multiple groups of friction coefficients, rotation speeds and rolling passes meeting the actual production requirements, and an optimal solution is selected for actual production.
On the other hand, the invention provides a bending forming process of in-situ nano reinforced high-strength ductile steel, which is characterized in that the bending forming process is determined by adopting any one of the implementation methods; the rolling pass of the roll bending process is 7, the rolling reduction of the upper roller is 187mm in total, the rolling reduction of each pass is the same, the friction coefficient is 0.2, and the rotating speed is 0.05 rad/s.
On the other hand, the invention also provides a bending forming process of the in-situ nano reinforced high-strength ductile steel, which is characterized by adopting any one of the implementation methods to determine; the rolling pass of the roll bending process is 5, the rolling reduction of the upper roller is 187mm in total, the rolling reduction of each pass is the same, the friction coefficient is 0.15, and the rotating speed is 0.05 rad/s.
Compared with the prior art, the invention can obtain the following technical effects: the manufacturing method can ensure the continuous process manufacturing method within the tolerance range, improve the roll bending forming effect of the plate, reduce the production cost, improve the production efficiency, has low technical risk, is beneficial to improving the forming quality of the plate, and provides a feasible method for realizing mass production of the in-situ nano reinforced high-strength and high-toughness steel thick plate cylinder; the three-section type roll bending and splicing are adopted, so that the stress of the plate can be released in the roll bending process, and the forming quality of the part and the reliability of the structure are greatly improved.
Of course, it is not necessary for any one product in which the invention is practiced to achieve all of the above-described technical effects simultaneously.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a flow chart of a method for implementing a bending process of in-situ nano-reinforced high-strength and toughness steel according to an embodiment of the present invention;
FIG. 2 is a distribution diagram of circumferential strain and residual stress of a high-toughness steel plate obtained in example 1 of the invention in a roll bending forming process; wherein, fig. 2(a) is a distribution diagram of circumferential strain, and fig. 2(b) is a distribution diagram of residual stress;
FIG. 3 is a distribution diagram of circumferential strain and residual stress of a high-toughness steel plate obtained in example 2 of the invention in a roll bending forming process; wherein, fig. 3(a) is a distribution diagram of circumferential strain, and fig. 3(b) is a distribution diagram of residual stress;
FIG. 4 is a distribution diagram of circumferential strain and residual stress of a high-toughness steel plate obtained in example 3 of the invention in a roll bending forming process; fig. 4(a) is a distribution diagram of circumferential strain, and fig. 4(b) is a distribution diagram of residual stress.
[ detailed description ] embodiments
For better understanding of the technical solutions of the present invention, the following detailed descriptions of the embodiments of the present invention are provided with reference to the accompanying drawings.
It should be understood that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, such as the same or similar components or process adaptations, which can be made by one of ordinary skill in the art based on the embodiments of the present invention without any inventive step, are within the scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The invention provides a method for realizing the bending forming process of in-situ nano reinforced high-strength ductile steel, which ensures the roll bending forming quality of a plate, provides relevant forming parameters and relevant process measures for controlling the springback quantity of the plate for the subsequent workpiece production process of the steel plate, improves the forming efficiency and the forming rate of the plate, reduces the processing trial-production time, saves resources and provides technical guidance for the bending forming of a thick plate under the actual production condition.
The invention can realize the realization method of the bending forming process of the in-situ nano reinforced high-strength ductile steel, adopts the manufacturing method of roll bending forming, but the bending process of the thick plate cylinder is complex, the thick plate cylinder is directly bent into the cylinder, the shape change is severe, the stress strain distribution is uneven, the stress can not be well released, the residual stress of the formed part is overlarge and the bending degree is large, and the service performance of the formed part is influenced. The method comprises the steps of firstly dividing a thick plate cylinder into three sections according to the structural form of the thick plate cylinder to be formed, then performing roll bending on each section, wherein the roll bending process schemes of the three sections of circular arcs are the same, and welding and assembling the three sections of circular arcs after the roll bending is completed to perform an actual process test. The plate is spliced after the three-section type roll bending, so that the stress of the plate is released in the roll bending process, the forming quality of parts and the reliability of the structure are greatly improved, the energy is saved, the efficiency is high, the technical risk can be reduced, and the forming property and the forming precision are obviously improved.
The application discloses a method for realizing a bending forming process of in-situ nano reinforced high-strength ductile steel, which comprises the following steps of:
step one, calculating the curvature radius before springback according to the curvature radius of a plate to be formed; such as the formula:
where rho1-radius of curvature of the sheet after springback, ρ0-radius of curvature of the sheet before springback, n-hardening index; E-Young's modulus, GPa; t-the thickness of the plate; a-a correction factor; sigmas-yield strength, MPa; b ═ n +2) E.
In this patent, n is 0.038 and σ iss＝824.1MPa，t＝45mm，E＝204GPa，a＝1.75×10-5。
Step two, determining the pressing amount of the upper roller according to the radius of curvature before springback, as a formula:
ρ0＝-0.0039X3+2.5239X2-550.34X+41794 (2)
wherein X represents the pressing amount of the upper roller.
And step three, determining the downward pressing quantity of the upper roller according to the step one and the step two, performing orthogonal tests on key process parameters such as the friction coefficient mu, the rotating speed omega, the rolling pass n and the like, and substituting the optimal solution of the process parameters into a model established by ABAQUS finite element analysis software for operation. According to the model of the actual production equipment and the production experience (namely historical data), the friction coefficient mu is 0.15-0.25, the rotating speed omega is 0.05-0.07 rad/s, and the rolling pass n is 5-7.
And step four, comparing the circumferential strain distribution and the residual stress distribution of the roll bending forming piece under different process parameters so as to judge the forming precision and the forming performance of the plate, and selecting the optimal scheme for guiding the actual production.
The circumferential curvature distribution of the plate after roll bending forming cannot be directly obtained through ABAQUS, the calculation of the curvature radius of the plate after roll bending forming through a three-point coordinate method is complicated, and the workload of calculating the curvature radius of the whole circumferential direction of the plate is too large, so that the calculation of the circumferential curvature radius of the plate after roll bending forming through the three-point coordinate method is unrealistic. If the curvature radius of the plate material is consistent after forming, the deformation amount of the plate material is consistent, so the forming precision can be described by the circumferential strain of the plate material. The residual stress after the plate is formed can reflect the forming performance of the plate, and the proper residual stress can improve the fatigue strength of the structural member obtained after the plate is roll-bent and formed.
And comprehensively reflecting the forming performance of the plate according to the two indexes, and further judging whether the simulated forming process can be used for actual production.
And if different friction coefficients, rotating speeds and rolling passes are input into the model for simulation to obtain multiple groups of friction coefficients, rotating speeds and rolling passes meeting the actual production requirements, performing orthogonal tests on the multiple groups of friction coefficients, rotating speeds and rolling passes meeting the actual production requirements, and selecting the optimal solution for actual production.
The following assumptions were made during the sheet roll-forming analysis: (1) the width of the roller and the plate is sufficiently wide, the width of the plate is far larger than the thickness of the plate, and the roll bending process is treated as a plane strain problem; (2) the roller does not deform in the roll bending process and is regarded as a rigid body; (3) neglecting the temperature effect caused in the deformation process of the plate, and assuming that the material characteristic is room temperature; (4) assuming a constant friction coefficient and a static friction law in the roll bending process; (5) the angular velocities of the three rolls remain constant during the roll bending process. A two-dimensional modeling mode is adopted for plane strain problem treatment, the length of a plate is set to be 4740mm according to the size of a target structural member in the three-roller plate bending machine, the plate needs to be designed in a segmented mode in order to eliminate straight edge problems in the actual production process, namely, the plate is divided into reserved sections at two ends and a middle forming section, the length of the forming section is determined according to the specification of a required structural member, and the length of the reserved sections is determined according to the actual model of the three-roller plate bending machine.
By utilizing an isotropic/motion hardening material model and combining a master-slave contact algorithm, the friction between the plate and the rollers is assumed to meet the Coulomb friction law, the friction coefficient is assumed to be constant, namely the friction coefficient between the upper roller and the upper surface of the plate and between the left lower roller and the lower surface of the plate and the friction coefficient between the left lower roller and the right lower roller and the lower surface of the plate, and the temperature change of the plate caused by friction in the roll bending forming process is ignored. All loads and constraints in the roll bending forming simulation model take a global coordinate system as reference, and the simulation process is divided into two procedures of pressing and roll bending. The upper roller is pressed downwards to bend the plate, the three rollers roll simultaneously to make the plate generate rolling deformation, and the rigid movement of the rollers is applied to the reference points of the rollers. The boundary condition and the load are restrained by two modes of displacement/rotation and speed/angular speed, in the pressing process, the upper roller only keeps the degree of freedom in the y direction of the global coordinate system, and the left lower roller and the right lower roller fix all the degrees of freedom; in the roll bending process, the upper roller rotates around the z direction of the global coordinate system, the left lower roller and the right lower roller rotate around the z direction of the global coordinate system, and the positive and negative directions of the angular speed of the upper roller and the lower roller are determined according to the advancing direction of the plate in the roll bending process. The grid division adopts a quadrilateral structured grid division technology, the 4-node bilinear plane strain reduction integration unit (CPE4R) is utilized to simulate the shearing self-locking phenomenon in the bending forming process when the structural member bears the bending load effect.
Example 1:
the invention relates to a method for realizing a bending forming process of in-situ nano reinforced high-strength ductile steel, which comprises the following specific processes:
1) the plate is a 45mm thick plate, and the radius R1 of the upper working roll is 800 mm; the radius R2 of the lower working roll is 500 mm-R3; the distance between the centers of circles of R2 and R3 is 1600mm, and the arc plates are bent into 1/3 arc plates with the radius of 1500 mm;
2) the roll bending pass n is 5, the total reduction is 187mm, and the reduction of each pass is the same;
3) the friction coefficient is mu equal to 0.2, and the rotating speed is omega equal to 0.05 rad/s;
4) the circumferential strain distribution after roll bending is shown in fig. 2(a), and the residual stress distribution after bend bending is shown in fig. 2 (b). In fig. 2(a), the strain distribution of the rolling bending section of the plate material is uniform and close to a fixed value, which indicates that the difference of the curvature radius is small and close to the fixed value, so that the rolling bending process can be judged to obtain structural members with the same curvature radius at each position; the residual stress diagram in fig. 2(b) illustrates that the residual stress distribution of the formed plate on the cross section at different positions in the roll bending area has almost no obvious difference and is kept between 250 and 350MPa, and the formed plate is judged to have uniform stress distribution and stable performance.
Example 2:
the invention relates to a method for realizing a bending forming process of in-situ nano reinforced high-strength ductile steel, which comprises the following specific processes:
1) the plate is a 45mm thick plate, and the radius R1 of the upper working roll is 800 mm; the radius R2 of the lower working roll is 500 mm-R3; the distance between the centers of circles of R2 and R3 is 1600mm, and the arc plates are bent into 1/3 arc plates with the radius of 1500 mm;
2) the roll bending pass n is 7, the total reduction is 187mm, and the reduction of each pass is the same;
3) the friction coefficient is mu equal to 0.2, and the rotating speed is omega equal to 0.05 rad/s;
4) the distribution of the circumferential strain after bending is shown in fig. 3(a), and the distribution of the residual stress after bending is shown in fig. 3 (b). In fig. 3(a), the strain distribution of the rolling bending section of the plate material is uniform and close to a fixed value, which indicates that the difference of the curvature radius is small and close to the fixed value, so that the rolling bending process can be judged to obtain structural members with the same curvature radius at each position; the residual stress diagram in fig. 3(b) illustrates that the residual stress distribution of the formed plate on the cross section at different positions in the roll bending area has almost no obvious difference and is kept between 250 and 350MPa, and the formed plate is judged to have uniform stress distribution and stable performance.
Example 3:
the invention relates to a method for realizing a bending forming process of in-situ nano reinforced high-strength ductile steel, which comprises the following specific processes:
1) the plate is a 45mm thick plate, and the radius R1 of the upper working roll is 800 mm; the radius R2 of the lower working roll is 500 mm-R3; the distance between the centers of circles of R2 and R3 is 1600mm, and the arc plates are bent into 1/3 arc plates with the radius of 1500 mm;
2) the roll bending pass n was 5, and the total reduction was 187mm, and the reduction per pass was the same.
3) The friction coefficient is mu equal to 0.15, and the rotating speed is omega equal to 0.05 rad/s;
4) the distribution of the circumferential strain after bending is shown in fig. 4(a), and the distribution of the residual stress after bending is shown in fig. 4 (b). In fig. 4(a), the strain distribution of the rolling bending section of the plate material is uniform and close to a fixed value, which indicates that the difference of the curvature radius is small and close to the fixed value, so that the rolling bending process can be judged to obtain structural members with the same curvature radius at each position; the residual stress diagram in fig. 4(b) illustrates that the residual stress distribution of the formed plate on the cross section at different positions in the roll bending area has almost no obvious difference and is kept between 250 and 350MPa, and the formed plate is judged to have uniform stress distribution and stable performance.
According to the three embodiments, the circumferential strain of the formed plate roll bending section is uniform and close to a fixed value, the curvature radius of each position of the structural part is the same, the residual stress is kept between 250 MPa and 350MPa, and the structural part with the target size can be obtained according to the roll bending speed, the roll bending pass and the friction coefficient range provided by the three embodiments, and the forming performance is good.
The implementation method of the bending forming process of the in-situ nano reinforced high-strength and tough steel provided by the embodiment of the application is described in detail above. The above description of the embodiments is only for the purpose of helping to understand the method of the present application and its core ideas; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
As used in the specification and claims, certain terms are used to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. "substantially" means within an acceptable error range, and a person skilled in the art can solve the technical problem within a certain error range to substantially achieve the technical effect. The description which follows is a preferred embodiment of the present application, but is made for the purpose of illustrating the general principles of the application and not for the purpose of limiting the scope of the application. The protection scope of the present application shall be subject to the definitions of the appended claims.
It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a commodity or system that includes the element.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
The foregoing description shows and describes several preferred embodiments of the present application, but as aforementioned, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the application as described herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the application, which is to be protected by the claims appended hereto.
Claims (10)
1. A method for realizing a bending forming process of in-situ nano reinforced high-strength ductile steel is characterized by comprising the following steps:
s1, calculating the curvature radius before springback according to the curvature radius of the plate to be formed;
s2, determining the pressing amount of the upper roller according to the curvature radius before springback;
s3, inputting the pressing amount of the upper roller, the friction coefficient, the rotating speed and the rolling pass into a model established by finite element analysis software for simulation operation to obtain a simulation result;
s4, analyzing the circumferential strain distribution and residual stress distribution of the roll bending formed plate in the simulation result to obtain the forming precision and forming performance of the roll bending formed plate;
s5, judging whether the forming precision and the forming performance of the roll bending formed plate meet the requirements of actual production or not; if the rolling-bending forming plate meets the requirements, applying the values of the upper roller pressing amount, the friction coefficient, the rotating speed and the rolling pass corresponding to the rolling-bending forming plate to actual production; otherwise, the friction coefficient, the rotation speed and the rolling pass are adjusted, and the process re-enters S3.
2. The method for realizing the bending forming process of the in-situ nano reinforced high-strength ductile steel according to claim 1, wherein the formula for calculating the curvature radius before springback in the step S1 is as follows:
in the formula, ρ1Radius of curvature of the sheet to be formed, p0-radius of curvature of the sheet before springback, n-hardening index; t-the thickness of the plate; a-a correction factor; sigmas-yield strength, MPa; b ═ n +2) E, E young's modulus, GPa.
3. The method for realizing the bending forming process of the in-situ nano reinforced high-strength ductile steel as claimed in claim 2, wherein the relation between the radius of curvature before springback and the pressing amount of the upper roller in S2 is as follows:
ρ0＝-0.0039X3+2.5239X2-550.34X+41794 (2)
in the formula, X-the amount of pressing down of the upper roll, rho0-radius of curvature of the sheet before springback.
4. The method for realizing the bending forming process of the in-situ nano reinforced high-strength ductile steel according to claim 1, wherein the value ranges of the friction coefficient, the rotating speed and the rolling pass are determined according to parameters of actual production equipment and historical data.
5. The method for realizing the bending forming process of the in-situ nano reinforced high-strength ductile steel according to claim 4, wherein the friction coefficient ranges from 0.15 to 0.25, the rotating speed ranges from 0.05 to 0.07rad/s, and the rolling pass ranges from 5 to 7.
6. The method as claimed in claim 2, wherein n is 0.038, σ, and the bending process is performed on the steels＝824.1MPa，t＝45mm，E＝204GPa，a＝1.75×10-5。
7. The method for realizing the bending forming process of the in-situ nano reinforced high-strength ductile steel according to claim 1, wherein the values of the upper roll reduction, the friction coefficient, the rotation speed and the rolling pass in the step S5 are applied to actual production: dividing the cylinder into three sections according to the structural data of the plate cylinder to be formed, and performing roll bending on each section independently, wherein the roll bending process of the three sections adopts the upper roller pressing amount, the friction coefficient, the rotating speed and the rolling pass obtained in the step; and after the roll bending is finished, welding and assembling the three sections of circular arcs, and then performing subsequent processes.
8. The method for realizing the bending forming process of the in-situ nano reinforced high-strength ductile steel according to claim 1, wherein if different friction coefficients, rotation speeds and rolling passes are input into a model for simulation to obtain a plurality of groups of friction coefficients, rotation speeds and rolling passes which meet actual production requirements, orthogonal tests are carried out on the plurality of groups of friction coefficients, rotation speeds and rolling passes which meet the actual production requirements, and an optimal solution is selected for actual production.
9. A bending forming process of in-situ nano reinforced high-strength ductile steel is characterized by being determined by the implementation method of any one of claims 1 to 8; the rolling pass of the roll bending process is 7, the rolling reduction of the upper roller is 187mm in total, the rolling reduction of each pass is the same, the friction coefficient is 0.2, and the rotating speed is 0.05 rad/s.
10. A bending forming process of in-situ nano reinforced high-strength ductile steel is characterized by being determined by the implementation method of any one of claims 1 to 8; the rolling pass of the roll bending process is 5, the rolling reduction of the upper roller is 187mm in total, the rolling reduction of each pass is the same, the friction coefficient is 0.15, and the rotating speed is 0.05 rad/s.
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